جستجوی مقالات مرتبط با کلیدواژه « Gomishan wetland » در نشریات گروه « زیست شناسی »

Body size is a fundamental characteristic of organisms and is expected to decrease in response to environmental stresses such as heat stress, and its estimation is an important step in addressing many ecological questions in aquatic environments. The aim of this study was to investigate the effect of environmental factors on body size and diversity of macrobenthos communities in Gomishan wetland and Miankaleh Bay. For this purpose, macrobenthos was carried out by leaf packages in summer 2017. The results showed that the average temperature, salinity and electrical conductivity in Gomishan lagoon were higher than Miankale Bay, but no difference was observed in terms of dissolved oxygen and pH. The average dry weight and total length of the Zygoptera showed no significant difference, Shannon's species diversity and evenness indices showed a significant difference in two ecosystems. The results of covariance analysis between dissolved oxygen, salinity, body weight and abundance on leaf pack decomposition showed that only water salinity has an inverse relationship with the decomposition rate. The results of factorial rotation matrix showed that temperature, longitude and latitude and k-day had a positive effect and pH, salinity and oxygen had a negative effect on the abundance of macrobenthos. The results showed that the changes in environmental parameters such as temperature had an effect on the metabolism and weight of the biomass of different species, so that the average weight of many different species in the warmer water of Gomishan Lagoon was lower than that of Miankaleh Bay.

Heavy metals are non-biodegradable and tend to accumulate in tissues of organisms such as fish. Considering the various health risks and the nutritional benefits associated with fish consumption; assessment of heavy metals in fish tissues is important. The present study aims to measure and assess lead and cadmium concentrations in the muscles of Liza saliens from the Gomishan International Wetland. We collected 23 Liza saliens samples from 9 stations in different locations. The muscle samples were prepared by acid digestion (HNO3 and HCLO4) for analysis by graphite furnace atomic absorption spectroscopy (GFAAS). Mean concentration of cadmium was 163.26 ± 35.82 and lead was 12.46 ±8.62 μg/g dry weight. No significant correlation existed between lead and cadmium concentrations with body weight. The highest concentrations of these metals were detected in stations of the west and center of wetland that seemed to be caused by the transfer of pollutants from the Caspian Sea to the wetland. The concentration of cadmium and lead were lower than the standard levels suggested by WHO, FAO, UK (MAFF) and NHMRC. Currently, no risk to human health from the consumption of fish tissue was not determined. Therefore, consumption of Grey Mullet does not have any risk to human health.

The reproductive biology of the genus Knipowitschia caucasica was examined from Gomishan wetland a period of one year (2006-2007). Some reproductive characteristics like، number of undifferentiated، previtellogenic stage، vitellogenic stage and postvitellogenic oocytes، and GSI index were examinedThis species are as important food for economic fish species in Caspian sea، specially for Acipenserid species. Different samples were taken from Gomishan wetland during one-year period of study. At this stage، the number of undifferentiated، previtellogenic stage، vitellogenic stage and postvitellogenic oocytes، and oocytes were counted. The number and diameter of ovary، nucleus and nucleolus were also measured. Data were analyzed using Systat statistical software. Results indicated that Knipowitschia caucasica was (p <0. 05) with respect to the numbers of differentiated and previtellogenic oocytes، and the diameter of Chorion and fulicule layers. GSI measurement showed that peak sexual maturity in this species was occurred in February.

Benthos communities play an important role in the food chain wetlands ecosystem, and the study of the communities are suitable criteria for assessing the ecological status of an aquatic ecosystem. In this study, the identification, abundance and biomass of Gomishan wetland benthos monthly was studied at three stations in autumn 2010 (from October to end of November). Sampling at each station (with triplicates) done by Van Veen Grab sampler and fixed with a ratio of 4% formalin and transported to the laboratory for later testing. During this study, four families Chironomidae, Neritidae, Planorbidae and Pyrgulidae were identified. The results of the study of the abundance and biomass of benthos at different Stations showed that Pyrgulidae family than other families had the highest abundance and biomass. Benthos of Planorbidae family was not observed At Station 2 at throughout the sampling month and station 1 at November. The results indicate that about 55% of the benthos abundance or dominance belongs to the Pyrgulidae family in Gomishan wetland.

The reproductive biology of the Neogobius pallasi (Berg، 1916) was examined from Gomishan wetland a period of one year (2006-2007). This species are as important food for economic fish species in Caspian sea، specially for Acipenserid species. Different samples were taken from Gomishan wetland during one-year period of study. At this stage، the number of undifferentiated، previtellogenic stage، vitellogenic stage and postvitellogenic oocytes، and oocytes were counted. The number and diameter of ovary، nucleus and nucleolus were also measured. Data were analyzed using Systat statistical software. Results indicated that Neogobius pallasi was (p <0. 05) with respect to the numbers of differentiated and previtellogenic oocytes، and the diameter of chorion layers. GSI measurement showed that peak of sexual maturity in this species occurred in June.

Gomishan wetland is a natural ecosystem located in 35 km north west of Gorgan, in the west vicinity of Khajeh Nafas city and Gomishan. Twice sampling from 3 different geographic positions in dry and rainy seasons, led to the isolation of 224 isolates. For 57 isolates, halophilic and halotolerant behaviors and also optimum and growth range in different pH and temperatures were determined. Most of the moderately halophilic and halotolerant strains were capable of growing optimally in media with pH 8.5-9 and optimum growth temperatures ranging from <4 to 40 °C. The isolates were examined for hydrolytic enzymes production. Most of the isolates showed lipase activites and a total of 15, 7 and 3 strains produced amylases, proteases and DNases, respectively. The enzymes could be useful in some industrial processes. 16S rDNA phylogenetic analysis were done for 55 strains. According to this analysis, strains were placed in 22 different genera: Achromobacter, Aeromicrobium, Altererythrobacter, Bacillus, Caenispirillum, Cyclobacterium, Erythrobacter, Halobacillus, Halomonas, Idiomarina, Jonesia, Marinobacter, Martelella, Nesiotobacter, Paenibacillus, Planococcus, Pseudomonas, Rheinheimera, Saccharospirillum, Stappia, Thalassospira and Vibrio. 23% of these strains were haloalkalophilic bacteria and belonged to the Bacillus, Halobacillus, Halomonas, Idiomarina and Marinobacter. This was the first study on the culturable bacteria at Gomishan wetland, an area of considerable alkaline thalassohaline ecosystem.